Crossing arm assembly

ABSTRACT

A crossing arm assembly that includes either one or two hollow, tapered fishing rod bodies cantilevered at their butt ends to a beam-mounting portion of a combined pivot/bracket. A crosspiece connects the tips of the rods. The combined pivot/bracket pivotally attaches to a support at the front end of a bus to block pedestrian traffic from crossing immediately in front of the bus when the bus is stopped. The rods are tapered in mass and cross-sectional area from their butt ends to their tips. The taper concentrates rod mass closer to the support to reduce the tendency of cantilevered rods to sag under their own weight and/or to swing forward as the bus decelerates. The taper also increases rod flexibility to prevent plastic rod deformation and to reduce loads on the support when external forces are applied to the rods. A flap is pivotally attached to one of the rods to increase beam visibility without adding significant wind resistance. The combined pivot/bracket has a U-shaped body with a vertical beam integrally connecting upper and lower pivot arms. A rod-mounting boss extends integrally outward from the beam. Upper and lower receptacles in the rod-mounting boss receive the butt ends of the two rods.

[0001] This is a continuation of U.S. Ser. No. 08/871,737 filed Jun. 9,1997.

TECHNICAL FIELD

[0002] This invention relates generally to safety equipment for schoolbusses and more particularly to a crossing arm assembly configured tomount on the front end of a school bus.

BACKGROUND OF THE INVENTION

[0003] School bus crossing arms are designed to extend to aperpendicular position relative to a front bus bumper when a school busstops to pick up or discharge passengers. In this perpendicularposition, such a crossing arm will block arriving and departingpassengers from crossing immediately in front of a school bus and belowthe bus driver's field of vision. U.S. Pat. No. 5,357,239, granted to meOct. 18, 1994, shows such a crossing arm assembly, or “safety gate,”that comprises a hollow or solid bar attached at one end to a plasticbracket. The plastic bracket is configured to pivotally mount the bar ona housing.

[0004] Others have attempted to provide improved crossing armarrangements. For instance, U.S. Pat. No. 4,697,541 granted Oct. 6, 1987to James H. Wicker discloses a crossing arm unit that comprises a shortpivot plate. The pivot plate is made of a sturdy, relatively heavy gagemetal (e.g. 3.5 in. of 14-gauge steel), a longer support plate ofrelatively light gauge metal (e.g. 20 in. of 0.08-in. aluminum plate)and a long U-shaped rod (e.g. 4 ft. of ¼-in. aluminum rod). The U-shapedrod serves as a pedestrian barrier. According to the Wicker patentspecification the crossing arm unit is light in weight to avoidstructural problems with its support. The unit is easily supported, issimple to construct and is economical to manufacture. The Wicker patent,at column 1, also states that crossing arms have been made oflightweight fiber glass rods and that the Wicker construction improveson these prior art constructions.

[0005] However, the Wicker construction is unduly complicatedparticularly when its assembly requirements are taken into account.Moreover, the long U-shaped rod is fragile, deforms easily and is proneto plastic rather than elastic deformation. The U-shaped rod alsorequires a strut that further complicates and adds to the expense of theWicker construction. Furthermore, the U-shaped rod has a narrow profileand is not highly visible.

[0006] U.S. Pat. No. 5,199,754 granted Apr. 6, 1993 to Lowell J. D.Freeman discloses a crossing arm or barrier whose construction includestubular fiberglass. While the Freeman crossing arm construction issimple in comparison to the Wicker construction, it includes only asingle rod that is heavy and rigid.

[0007] U.S. Pat. No. 3,153,398, granted Oct. 20, 1964 to George LaVemeRunkle and Gilbert S. Sheets, discloses a crossing arm structure thatcomprises a channel-shaped section of light sheet metal. Thechannel-shaped section is stiffened by a U-section having out-turnedlegs fixed to the back of the channel shaped section. The crossing armassembly is shaped to fit in a recess in the front bumper of a bus. Theassembly also includes a rubber guard structure that has a hollowrectangular center portion that is cemented to the channel section andflange portions that seal off the bumper recess.

[0008] This crossing arm structure is unduly complicated and expensiveto manufacture. Furthermore the arrangement requires a hinge structureto attach the crossing arm to the bumper. This hinge structure furthercomplicates construction and adds expense.

[0009] All the above designs have crossing arms that are cantilevered,i.e., supported by and extending rigidly from only one end. Therefore, aperson applying force near the free distal end of any of these arms hasa tremendous mechanical advantage over the mechanisms associated withthe support and can damage the support or permanently bend or break thearm. If not securely latched to the front of the bus, the inertia of thearm can cause it to swing forward from the bus, uncommanded, wheneverthe bus decelerates. In addition, an arm supported in this manner isprone to sagging under its own weight. Arm weight can also make itdifficult to dampen oscillations that occur when arm rotation is stoppedabruptly in the perpendicular extended position.

[0010] Therefore, what is needed is a crossing arm that is less massiveand therefore has less momentum to cause it to swing forward wheneverits host bus stops or slows in traffic. What is also needed is acrossing arm that resists sagging, is configured to withstandconsiderable abuse, e.g., hinge damage that can result when force isapplied along the length of the arm, and is economical to manufacture.

INVENTION SUMMARY

[0011] In accordance with this invention a crossing arm assembly isprovided that includes a mass-tapered cantilevered beam. The assemblyattaches to a support at the front end of a bus to block pedestriantraffic from crossing immediately in from of the bus when the bus isstopped. The crossing arm assembly comprises a combined pivot/bracketthat is pivotally attachable to the support. The combined pivot/bracketalso includes a beam-mounting portion. The elongated cantilevered beamhas a length extending between a beam inner end and a beam outer end.The beam is supported at the beam inner end on the beam-mounting portionof the combined pivot/bracket. The beam is generally mass tapered alongthe beam length from the beam inner end to the beam outer end. The masstaper concentrates beam mass closer to the support to reduce thetendency of the beam to sag under its own weight and/or to swing forwardas the bus decelerates.

[0012] According to another aspect of the invention, the cantilever beamis flexible. Cantilever beam flexibility may also increase as a functionof beam length as measured from the beam inner end toward the beam outerend. Beam flexibility prevents loads applied near the beam outer endfrom damaging the support or plastically (permanently) deforming thebeam.

[0013] According to another aspect of the invention, the beam is taperedin cross-sectional area from the inner end to the outer end. The taperincreases flexibility and reduces mass at the beam outer end. The taperobviates the need to construct the beam using a support plate or webbingbetween two separate parallel rods. The tapered configuration of thebeam is sufficiently strong to prevent sagging without using two rodswith an interconnecting plate or web.

[0014] According to another aspect of the invention, the beam includes afirst elongated rod. The first rod has a rod length that extends betweena rod butt end adjacent the beam inner end and a rod tip end adjacentthe beam outer end. The butt end of the first rod is connected to thebeam-mounting portion of the combined pivot/bracket. The rod providesstructural support for the beam.

[0015] According to another aspect of the invention, the first rod ismass tapered from the butt end to the tip end. The mass taper of the rodconcentrates rod mass closer to the beam inner end and the support. Thishelps reduce beam sag and the tendency for the beam to swing forward.

[0016] According to another aspect of the invention, the first rod istapered in cross-sectional area from the butt end to the tip end. Thishelps improve flexibility and reduce mass at the tip end of the firstrod.

[0017] According to another aspect of the invention, the first rod ishollow and has a closed geometric cross section. The hollow constructionsignificantly reduces rod mass.

[0018] According to another aspect of the invention, the first rod hasan elongated generally frusto-conical shape that is relatively easy andinexpensive to manufacture and provides an aerodynamic profile thatpresents very little wind resistance.

[0019] According to another aspect of the invention, the first rodcomprises flexible strips wound in a spiral pattern along the length ofthe rod. The spiral or helical application of the strips providesstrength and flexibility.

[0020] According to another aspect of the invention, the first rodcomprises a hollow fishing rod body. Fishing rod bodies are commerciallyavailable in great quantity and at low cost.

[0021] According to another aspect of the invention, a flap is pivotallyattached to the first rod. The flap makes the beam highly visible yetprovides little wind resistance. This reduces the problem of “windsailing” that occurs when wind gusts hamper the operation of a crossingarm or cause the arm to move, uncommanded.

[0022] According to another aspect of the invention, the flap comprisesa flap panel disposed below and extending radially downward from andparallel to the first rod. The flap panel may comprise rigid materialsuch as plastic and/or flexible material such as fabric.

[0023] According to another aspect of the invention, the flap comprisesa flap pivot tube integrally connected along the flap panel upper edge,the flap tube having first and second opposite openings, and a portionof the first rod is disposed within the tube. The tube provides a simpleengagement structure for pivotally suspending the flap from the firstrod. Annular plugs may be concentrically disposed in the flap tubeopenings to compensate for rod taper.

[0024] According to another aspect of the invention, a second elongatedrod may be attached at a butt end of the second rod to the beam-mountingportion of the combined pivot/bracket. The second rod is disposedgenerally parallel to and spaced below the first rod. A crosspiece maybe connected between the tip of the first rod and a tip of the secondrod. The resulting structure provides greater beam strength andvisibility.

[0025] According to another aspect of the invention, the combinedpivot/bracket includes two opposing pivot structures that are supportedcoaxially opposite each other on inner ends of respective upper andlower pivot arms of a U-shaped body. A vertical beam integrally connectsouter ends of the pivot arms and a rod-mounting boss extends integrallyoutward from an outer end surface of the beam. At least one rodreceptacle is formed in an outer end surface of the rod-mounting bossand the first rod butt end is disposed coaxially within the receptacle.This combined pivot/bracket construction is easy to manufacture andprovides strong, low profile support to the rods and flap.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To better understand and appreciate the invention, refer to thefollowing detailed description in connection with the accompanyingdrawings:

[0027]FIG. 1 is a perspective view of a crossing arm assemblyconstructed according to the present invention and attached to a schoolbus;

[0028]FIG. 2 is a fragmentary front view of the crossing arm assembly ofFIG. 1;

[0029]FIG. 3 is a perspective view of a first elongated rod of thecrossing arm assembly of FIG. 1;

[0030]FIG. 4 is a diagrammatic view of a first elongated rod of thecrossing arm assembly of FIG. 1;

[0031]FIG. 5 is a perspective view of a flap portion of the crossing armassembly of Fig.

[0032]FIG. 6 is a fragmentary front view of an outer end of the crossingarm assembly of FIG. 1;

[0033]FIG. 7 is a partially cut-away fragmentary front view of an innerend of the crossing arm assembly of FIG. 1;

[0034]FIG. 8 is a fragmentary top view of an inner end of the crossingarm assembly of FIG. 1;

[0035]FIG. 9 is a fragmentary, partial-cross-sectional end view takenalong line 9-9 of FIG. 7;

[0036]FIG. 10 is a front view of a vertical crosspiece of the crossingarm assembly of FIG. 1;

[0037]FIG. 11 is a view of the cross piece of FIG. 10 taken from alongline 11-11 in FIG. 10;

[0038]FIG. 12 is a view of the crosspiece of FIG. 10 taken from alongline 12-12 in FIG. 10; and

[0039]FIG. 13 is a fragmentary front view of an alternate crossing armassembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0040] A crossing arm mechanism is generally indicated at 10 in FIG. 1.The crossing arm mechanism 10 comprises a sealed electrical actuatorassembly 12 that is shown mounted on the front bumper 14 of a school bus16 opposite the driver side. A crossing arm assembly, constructedaccording to the present invention, is generally indicated at 18 inFIG. 1. The crossing arm assembly 18 is hinged on the actuator assembly12 for pivotal movement. The actuator assembly 12 pivots the crossingarm assembly 18 between a retracted (stored) position adjacent the frontbumper 14 of the school bus 16 and an extended (operative) position. Inthe operative position, the crossing arm assembly 18 extends outwardlyof the bus bumper 14 in a perpendicular fashion as shown in FIG. 1.

[0041] The actuator assembly 12 provides a tamper proof and weatherproofenvironment for several electrical and mechanical components. Thesecomponents include an electric motor and a motor control circuit forpivoting the crossing arm assembly 18 back and forth between the storedposition and the operative position.

[0042] The structure of the actuator assembly 12 is explained in detailin my copending U.S. patent application, Ser. No. 08/654,680 filed May29, 1996 which is incorporated herein by reference. Another suitableactuating device is shown in my prior U.S. Pat. No. 5,357,239 grantedOct. 18, 1994.

[0043] The crossing arm assembly 18 pivots to the operative position toblock pedestrian traffic from crossing immediately in from of the bus 16and beneath the driver's field of vision when the bus 16 is stopped. Asis best shown in FIGS. 7-9, the crossing arm assembly 18 comprises acombined pivot/bracket 20 configured for pivotal attachment to asupport, i.e., the actuator assembly 12. The combined pivot/bracket 20includes a beam-mounting portion 22. An elongated cantilevered beam 24is supported at a beam inner end 26 on the beam-mounting portion 22 ofthe combined pivot/bracket 20.

[0044] The beam 24 is generally mass tapered along a length of the beam24 from the beam inner end 26 to a beam outer end 28. The mass taperingconcentrates beam mass closer to the support 12 which reduces thetendency of the beam 24 to sag under its own weight and/or to swingforward as the bus 16 decelerates. In other words, with mass taperingthe beam outer end 28 carries less mass and therefore less momentum.Because there is less mass toward the outer end 28 of the beam 24, thebeam 24 sags less under its own weight and is less prone to swingforward, uncommanded, when the bus 16 decelerates.

[0045] The crossing arm assembly beam 24 is “mass tapered” in that itsmass per unit length generally decreases from the beam inner end 26 tothe beam outer end 28. Expressed mathematically, the beam mass may bedescribed as comprising a series of differential elements of mass. Eachdifferential element of mass may be assumed to be a thin plate ofuniform thickness made of homogeneous material of uniform density. Thedifferential elements of mass are aligned parallel to one another andperpendicular to an axis extending the length of the beam 24. “Masstapering,” then, is an array of differential elements of mass thatgenerally decrease in value as a function of beam length as measuredfrom the beam inner end 26 toward the beam outer end 28.

[0046] The cantilever beam 24 is flexible and elastically deformable.Cantilever beam flexibility increases as a function of beam length asmeasured from the beam inner end 26 toward the beam outer end 28. Inother words, the beam 24 is more flexible at its outer end 28 than it isat its inner end 26. Increased flexibility at the beam outer end 28reduces or eliminates plastic permanent) deformation in the beam 24 andreduces the amount of force transferred from the beam outer end 28 tothe actuator assembly 12. Forces exerted near the beam outer end 28result in elastic (temporary) beam 24 deformation and do not place highresultant loads on the actuator assembly 12. The inner end of the beam24 is stiffer to provide support for the outer end 28 and to preventsagging.

[0047] The beam 24 is tapered in cross-sectional area from the beaminner end 26 to the beam outer end 28. Expressed mathematically, thebeam volume comprises differential elements of volume that generallydecrease in value as a function of beam length as measured from the beaminner end 26 toward the beam outer end 28. Each element of volume isdefined by a uniform thickness and by the cross sectional area of thebeam 24 as measured at a given point along the beam length. Because thethickness of each differential volume element is the same, the crosssectional area of the volume elements decreases with the length of thebeam 24 as measured from the beam inner end 26 toward the beam outer end28.

[0048] The flexibility of the beam 24 is at least partly attributable tothe fact that the beam 24 is mass tapered by tapering thecross-sectional area of the beam 24 as described above. The narrowerportion of the tapered beam 24 is more flexible and elasticallydeformable because there is less beam material to resist bending.

[0049] As shown in FIGS. 2, 3 and 7-9, the beam 24 includes a firstelongated rod 30 having a rod length of approximately 66 inchesextending between a rod butt end 32 adjacent the beam inner end 26 and arod tip end 34 adjacent the beam outer end 28. The butt end 32 of thefirst rod 30 is connected to the beam-mounting portion 22 of thecombined pivot/bracket 20.

[0050] As best shown in FIG. 3, the first rod 30 is tapered in both massand cross-sectional area from the butt end 32 to the tip end 34. Thefirst rod 30 is also hollow and has a closed geometric cross section andan elongated generally frusto-conical shape. At its butt end 32, the rodmeasures approximately ¾″diameter. At its tip end 34, the rod measuresapproximately {fraction (3/16)}″.

[0051] In the diagram of FIG. 4 a mass tapered hollow frusto-conical rodis shown in phantom. As shown in the FIG. 4 diagram, the total rod massm may be described as comprising a series of differential elements ofmass dm. Each differential element of mass dm may be defined as a thinannular plate of uniform thickness dx and made of homogeneous materialof uniform density ρ. The differential thickness dx and across-sectional area A define each plate. The cross-sectional area A ofeach plate can be expressed as the difference between the area of acircle of radius r₁ and the area of a circle of radius r₂: A=π(r₁ ²−r₂²)dx. Therefore, each differential element of mass dm may be describedby the equation dm=ρπ(r₁ ²−r₂ ²)dx. As shown in FIG. 4, for a cone, r₁=a₁ ²/h² x² dx and r₂=a₂ ²/h² x² dx. Therefore, each differential elementof mass dm=ρπ x²/h² (a₁ ²−a₂ ²)dx.

[0052] The differential elements of mass dm are aligned parallel to oneanother and perpendicular to an x-axis extending coaxially along thelength of the first rod 30. The differential elements of mass dmgenerally decrease in value as a function of rod length l as measuredfrom the butt end 32 of the first rod 30 toward the tip end 34 of thefirst rod 30. In the FIG. 4 diagram, the butt end 32 of the first rod 30is disposed a distance b from the grid origin along the x-axis. The tipend 34 of the first rod 30 is disposed a distance h from the grid originalong the x-axis. Therefore, the total mass m of the first rod 30 may beexpressed as the integral, from h to b of the differential elements ofmass dm.

[0053] The first rod is a commercially available fishing rod bodycomprising flexible strips of fiberglass wound in a spiral pattern as isbest shown in FIG. 3. The rod 30 shown in the figures is one of manycommercially available fishing rod bodies that are suitable for use in acrossing arm assembly constructed according to the present invention.U.S. Pat. Nos. 4,015,360; 4,555,113; 5,076,004; 5,324,558; 5,538,769 and5,592,771 describe other suitable rod bodies.

[0054] An elongated flap, generally indicated at 36 in FIGS. 1, 2 and5-8, is pivotally attached to and suspended from the first rod 30. As isbest shown in FIG. 7, the flap 36 is colored with alternating diagonalblack 38 and yellow 40 safety stripes. The stripes make the beam 24 morevisible and help to identify the function of the beam 24. In otherembodiments, a plurality of flaps may be suspended from the first rod 30instead of a single long flap 36 as shown in FIG. 13.

[0055] The flap 36 comprises a rectangular flap panel 42 and acylindrical flap pivot tube 44. The flap panel 42 and pivot tube 44 areintegrally formed as a single unitary piece with the flap panel 42extending radially outward from and parallel to the pivot tube 44. Theflap pivot tube 44 is, therefore, integrally connected to the flap panel42 along an upper edge of the flap panel 42. The flap 36 is cut from anelongated extruded strip (not shown).

[0056] As is best shown in FIG. 5, there are openings 46 disposed ateither end of the flap tube 44 to allow each flap 36 to be slid onto thefirst rod 30 during assembly. Therefore, following assembly, a portionof the first rod 30 is disposed within the flap tube 44. In other words,the flap 36 is supported on the first rod 30 with the first rod 30extending through the flap pivot tube 44. The flap panel 42 is suspendedbelow and extends radially downward from and parallel to the first rod30. The clearance between the tapered outer diameter of the first rod 30and the inner diameter of the pivot tube 44 is sufficient to allow theflap 36 to swing freely on the first rod 30.

[0057] An annular plug, shown at 48 in FIG. 2, is concentrically andcoaxially supported within the opening 46 adjacent the tip of the firstrod 30. The plug 48 may be secured either by interference fit or anyother fastening means known in the art, e.g., by adhesive application orthreading. The plug 48 is slidably and rotatably disposed around thefirst rod 30. In other words, the clearance between the tapered outerdiameter of the first rod 30 and inner diameter of the annular plug 48is sufficient to allow the flap 36 to swing freely on the first rod 30.The plug 48 compensate for narrowing pole outer diameter and allows theflap tube 44 to be formed with a constant inner diameter along itslength.

[0058] A second elongated, hollow, frusto-conical rod, generallyidentical to the first rod 30, is generally indicated at 50 in FIGS. 1,2, 6, 7 and 9, has a butt end 52 attached to the beam-mounting portion22 of the combined pivot/bracket 20. The second rod 50 is disposedgenerally parallel to and is spaced approximately 3 ⅝″below the firstrod 30. This space between the two rods 30, 50 is sufficient to allowthe flap 36 to swing freely on the first rod 30 without contacting thesecond rod 50.

[0059] A rigid plastic vertical crosspiece, shown at 54 in FIGS. 1, 6,and 10-12, connects the tip 34 of the first rod 30 to a tip 56 of thesecond rod 50. The crosspiece 54 includes a main body portion 59 havingfirst and second crosspiece ends 58, 60. The first crosspiece end 58 isconnected to the tip of the first rod 30 and the second crosspiece end60 is connected to the tip 56 of the second rod 50. As shown in FIGS. 1and 6, the cross piece 54 holds the rod tips 34, 56 together and causesthe two rods 30, 50 to move together as a single beam 24 between thestored and operative positions. The main body 59 of the crosspiece 54 ishollow to minimize mass at the outer end 28 of the beam 24.

[0060] As is best shown in FIGS. 10 and 11, the crosspiece includes apair of annular posts 53. Each post 53 is hollowed to form a tipreceptacle 55 for receiving one of the rod tips 34, 56. An annularflap-spacer boss 57 is co-axially disposed around the post 53 adjacentthe first crosspiece end 58. The annular flap-spacer boss spaces theflap 36 approximately ⅛″away from the main body portion 59 of thecrosspiece 54 to prevent the flap 36 from contacting and binding on themain body portion 59 as the flap 36 swings from the first rod 30.

[0061] The rod tips 34, 56 are held in the receptacles 55 by adhesive.In other embodiments, the rod tips 34, 56 may be secured within thereceptacles 55 by a transverse setscrew or any other suitable retainingmeans known in the art.

[0062] As best shown in FIG. 7, the combined pivot/bracket 20 has aU-shaped plastic pivot portion. Two opposing pivot pins 62 are supportedcoaxially opposite each other on inner ends of respective upper 64 andlower 66 hollow pivot arms of the pivot portion. A hollow vertical beam68 integrally connects outer ends of the pivot arms 64, 66. A hollowrod-mounting boss portion of the combined pivot/bracket 20, shown at 70in FIGS. 7-9, extends integrally outward from an outer end surface ofthe vertical beam 68. The boss measures approximately 5″from a lower endof the boss to an upper end of the boss.

[0063] First and second outer receptacle apertures 72, 74 are formedthrough an outer end wall 77 of the rod-mounting boss 70 adjacent therespective upper and lower ends of the boss. First and second middlereceptacle apertures 73, 75 are formed through an outer vertical beamwall 79 in coaxial alignment with the outer receptacle apertures 72, 74.First and second square webs 81, 83 are formed within the vertical beam68 between an inner vertical beam wall 85 and the outer vertical beamwall 79. First and second inner receptacle apertures 87, 89 are formedthrough respective first and second webs 81, 83 and are coaxiallyaligned with the respective middle and outer receptacle apertures 73,75; 72, 74. The inner, middle and outer receptacle apertures are sizedand aligned to receive and hold the butt ends 32, 52 of the respectivefirst and second rods 30, 50.

[0064] To preclude the rod butt ends 32, 52 from sliding out of thereceptacle apertures, set screws 91 are threaded through each of twoscrew apertures 90, 92 in a back wall of the rod-mounting boss 70 andinto the respective rod butt ends 32, 52.

[0065] An annular boss 94 extends integrally outward approximately⅛″from the outer end wall 77 of the rod-mounting boss 70 and is disposedconcentrically around the first outer receptacle aperture 72. The firstand second rod butt ends 32, 52 are disposed coaxially within therespective upper and lower rod receptacles 72, 74. The first rod buttend 32 also passes through the annular boss 94. The annular boss 94spaces the flap 36 from the outer end wall 77 to prevent the flap fromcontacting and binding on the outer end wall 77.

[0066] The pivot portion of the combined pivot/bracket 20 measuresapproximately 11″from a lower surface of the lower pivot arm 66 to anupper surface of the upper pivot arm 64. The combined pivot/bracket 20measures approximately 6 ⅞″from a distal end of the upper pivot arm 64to the outer end surface of the boss portion 70. The crossing armassembly 18 measures approximately 72″from the upper pivot pin 82 to theouter end of the crosspiece 54.

[0067] As best shown in FIGS. 8 and 9, the combined pivot/bracket 20 isdivided into front 76 and rear 78 molded parts that are substantiallymirror images of each other. The combined pivot/bracket parts 76, 78 aresecured together to form the combined pivot/bracket 20. As shown in FIG.7, each hollow pivot arm 64, 66 holds a plastic elbow 80 that includes avertical pivot pin 82. Each vertical pivot pin 82 extends outwardly ofan integral circular flange 84. Opposite faces of each flange 84 engagethe pivot arm 64, 66 and a journal portion 86 of the actuator assembly12, respectively. A flanged brass bearing ring 88 may be providedbetween each flange 84 and the journal portion 86 of the actuatorassembly 12.

[0068] In other embodiments, the second rod 50, the vertical crosspiece54, and the flap 36 may be omitted

[0069] In other embodiments, the mass tapering of the individual rods30, 50 and/or the beam 24 may not be linear. In other words, the ratethat the mass of each differential mass unit decreases along the lengthof the beam 24 may vary. In fact, the mass may actually increase atcertain points along the beam 24 so long as the overall trend is adecrease in mass from the beam inner end 26 to the beam outer end 28. Inaddition, the cross-sectional size and shape of either or both rods 30,50 may vary with length.

[0070] In other embodiments, the first 30 and second 50 rod need not beidentical. In addition, the first rod 30 and/or second rod 50 could besolid to increase rod strength. However, this strength increase would beaccompanied by an increase in mass. The construction of either or bothrods 30, 50 could include other suitable materials such as graphite inaddition to or in place of fiberglass.

[0071] The flap panels 42 may comprise a flexible material such as anoilcloth fabric rather than rigid plastic. Rather than being identicalto one another, the flap panels 42 may have flap tubes of graduateddiameters to compensate for decreased rod diameter toward the tip end 34of the first rod 30.

[0072] The description and drawings illustratively set forth mypresently preferred invention embodiments. I intend the description anddrawings to describe these embodiments and not to limit the scope of theinvention. Obviously, it is possible to modify these embodiments whileremaining within the scope of the following claims. Therefore, withinthe scope of the claims, one may practice the invention otherwise thanas the description and drawings specifically show and describe.

We claim:
 1. A crossing arm assembly that pivotally attaches to asupport at the front end of a bus to block pedestrian traffic fromcrossing immediately in from of the bus when the bus is stopped, thecrossing arm assembly comprising: a combined pivot/bracket pivotallyattachable to the support, the combined pivot/bracket including a beammounting portion; an elongated cantilevered beam having a lengthextending between a beam inner end and a beam outer end, the beamsupported at the beam inner end on the beam mounting portion of thecombined pivot/bracket; the beam being generally mass tapered along thebeam length from the beam inner end to the beam outer end to concentratebeam mass closer to the support to reduce the tendency of the beam tosag under its own weight and/or to swing forward as the bus decelerates,the beam including a flexible elongated rod having a rod lengthextending between a rod butt end adjacent the beam inner end and a rodtip end adjacent the beam outer end, the butt end of the first rodconnected to the beam mounting portion of the combined pivot/bracket,and the first rod comprising a hollow, elongated frusto-conical tube. 2.A crossing arm assembly as defined in claim 1 in which the flexibleelongated rod is mass tapered from the butt end to the tip end.
 3. Acrossing arm assembly as defined in claim 1 in which the flexibleelongated rod is tapered in cross-sectional area from the butt end tothe tip end.
 4. A crossing arm assembly as defined in claim 1 in whichthe flexible elongated rod is hollow and has a closed geometric crosssection.
 5. A crossing arm assembly as defined in claim 1 in which theflexible elongated rod has an elongated generally frusto-conical shape.6. A crossing arm assembly that pivotally attaches to a support at thefront tend of a bus to block pedestrian traffic from crossingimmediately in front of the bus when the bus is stopped, the crossingarm assembly comprising: a combined pivot/bracket pivotally attachableto the support, the combined pivot/bracket including a beam mountingportion; an elongated cantilevered beam having a length extendingbetween a beam inner end and a beam outer end, the beam supported at thebeam inner end on the beam mounting portion of the combinedpivot/bracket; the beam being pivotally mass tapered along the beamlength from the beam inner end to the beam outer end to concentrate beammass closer to the support to reduce the tendency of the beam to sagunder its own weight and/or to swing forward as the bus decelerates, thebeam including a flexible elongated rod having a rod length extendingbetween a rod butt end adjacent the beam inner end and a rod tip endadjacent the beam outer end, the butt end of the first rod connected tothe beam mounting portion of the combined pivot/bracket, a flap beingpivotally attached to the first rod, the flap extending substantiallyfrom the butt end to the tip end of the first rod.
 7. A crossing armassembly as defined in claim 6 in which the flap comprises: one or moreflap panels disposed below and extending radially downward from andparallel to the first rod; and each of the one or more flap panelshaving a flap pivot tube integrally connected along an upper edge of theflap panel, the flap panel tube having first and second oppositeopenings, and a portion of the first rod is disposed within the tube. 8.A crossing arm assembly as defined in claim 7 in which the flap pivottube of each of the one or more flap panels has a constant innerdiameter, an annular plug is concentrically disposed in at least one ofthe first and second openings of the flap pivot tube and the plug isslidably and rotatably disposed around the hollow flexible elongatedfursto-conical tube of the first rod to compensate for outer diameterchanges of the frusto-conical tube.
 9. A crossing arm assembly asdefined in claim 1 and including a second elongated flexible rod havinga length extending between a butt end and a tip end of the second rod,the butt end of the second rod attached to the beam-mounting portion ofthe combined pivot/bracket, the second rod disposed generally parallelto and spaced below the first rod.
 10. A bus having crossing armassembly that is pivotally attached to a support at the front end of thebus to block pedestrian traffic from crossing immediately in front ofthe bus when the bus is stopped, the crossing arm assembly comprising: acombined pivot/bracket pivotally attachable to the support, the bracketincluding a beam mounting portion; an elongated flexible rod having arod length extending between a butt end and a tip end of the first rod,the butt end of the first rod connected to the beam mounting portion ofthe combined pivot/bracket; the elongated flexible rod being generallytapered in mass and in cross-sectional area from the butt end to the tipend.
 11. The crossing arm assembly as defined in claim 10 in which theelongated flexible rod is hollow and has an elongated generallyfrusto-conical shape.
 12. A crossing arm assembly that pivotallyattaches to a support at the front end of a bus to block pedestriantraffic from crossing immediately in front of the bus when the bus isstopped, the crossing arm assembly comprising: a combined pivot/bracketpivotally attachable to the support, the combined pivot/bracketincluding a pivot portion and a boss portion; a first elongated flexiblerod having a rod length extending between a butt end and a tip end ofthe first rod, the butt end of the first rod connected to the bossportion of the combined pivot/bracket; a second elongated flexible rodhaving a length extending between a butt end and a tip end of the secondrod, the butt end of the second rod attached to the boss portion of thecombined pivot/bracket, the second rod spaced below the first rod; thefirst and second rods being generally mass tapered along the respectivelengths of the rods from the respective rod butt ends to the respectiverod tip ends.
 13. A crossing arm assembly as defined in claim 12 inwhich the first and second rods are tapered in cross-sectional area fromthe respective butt ends of the rods to the respective outer ends of therods.
 14. A crossing arm assembly as defined in claim 12 in which thefirst and second rods are hollow and have respective closed geometriccross sections
 15. A crossing arm assembly that pivotally attaches to asupport a the front end of a bus to block pedestrian traffic fromcrossing immediately in front of the bus when the bus is stopped, thecrossing arm assembly comprising: a combined pivot/bracket pivotallyattachable to the support, the combined pivot/bracket including a pivotportion and a boss portion; a first elongated flexible rod having a rodlength extending between a butt end and a tip end of the first rod, thebutt end of the first rod connected to the boss portion of the combinedpivot/bracket; a second elongated flexible rod having a length extendingbetween a butt end and a tip end of the second rod, the butt end of thesecond rod attached to the boss portion of the combined pivot/bracket,the second rod spaced below the first rod; and a cross piece having afirst end connected adjacent the tip end of the first rod and a secondend connected adjacent the tip end of the second rod.